Images are an integral part of your WordPress posts and pages if you don't use them at this moment start using them now.
They work great for readability and for spicing up your blog posts and pages.
I use a lot of images like screenshots and featured images on this website, just to make it easier for you to understand the things I talk about.
WordPress Media Library
To go to the WordPress Media Library choose the Dashboard menu Media -> Library.
You then get an overview of all the images you already uploaded to your WordPress website.
Keep in mind that you can upload standard files like images (*.jpg, *.gif,*png, etc.), PDF's and Office documents (Word, Excel, PowerPoints, etc.).
The location of these images are set in the Dashboard option Setting -> Media along with the standard thumbnail sizes that are created after you uploaded and image.
You can add images into the Library directly or you upload them while you write your post or page.
You can add images in bulk by selecting the files and by just dragging and dropping them into the Library.
Adding Images / Documents into Posts or Pages
I personally don't like to upload images upfront into the Library, I always add the images while I write and add them during the writing process.
That way I always use the images I have uploaded, no unattached documents that just sit there taking away space in my hosting account.
You can insert any media using the Add Media button and then click the Upload Files tab.
As you can see in the image above there is an upload size limit on this account of 2 MB.
If you upload images to make them fit and in the same size as you want to publish them, you can have bigger images to link to, but try not to make them to large. Your page loading time will suffer dramatically if you load full images of these sizes!
You can select multiple images from your local hard disk and upload them in one go.
After the upload you choose Insert into post and the images are loaded based on your latest preferred sizing option.
Resizing Images in WordPress
You can change these settings and option, including the alt text, if you upload the file and if you choose to edit the image. You can do this from inside your post and also by going directly to the WordPress Media Library.
To edit the image data hover over the image and choose Edit.
If you choose to edit the information you can also change how the image is outlined, what the Alt text should be, which file size you want to display and even where the file should link to!
In the example sizes below I first point to the full image using the link to media file option, except for the large images, that goes to this sites Homepage using the Custom URL option from the Link to drop-down menu.
In the latest version of WordPress you can edit the images to a small extent. You have options to Resize the file, Crop part of the image, rotate the image and extend or compress it.
If you use one of these options, look at the options below on which files your changes should be affecting.
For me, these options are to limited so I use Corel Paintshop Pro to work and improve the images and free software of Irfanview for any resizing. I found the later to be the best software to do that resizing, even better than Photoshop.
How to Increase the Maximum File Upload Size
As you could see before, my file upload size is 2 MB, which works fine for me but could be too limited for you.
If you want to show people your photo's you might want to give them a higher resolution image that possible would exceed that size limit.
WPBeginner.com has a great article with several options on how you can increase that limit. http://www.wpbeginner.com/wp-tutorials/how-to-increase-the-maximum-file-upload-size-in-wordpress/
For my site, the php.ini file option in the root of my domain files folder worked best, as for many other people as well. If you don't want to create such a file but still need a larger file upload size then contact your hosting provider and ask if they are willing to changes that for you.
Where to get Images for Your WordPress Website
Finding images that you can use on your website is not difficult, but you should not use Google Image search for that!
You might end up getting a large bill because you used a copyrighted image… so check out sites like Imageafter.com for free images that have almost no limitation in its usage.
Most of my images come from Imageafter.com and Photodune.net and of course my own screenshots and photography!