Don't panic, it took me a year to figure it out...
works sort of like this, even though I will probably miss a part:
have picture(s) on your computer (best to have them down sized here)... also need to note where on your computer they are... in what file exactly....
make an account at one of these internet host sights, many are free because you get all kinds of adds jumping out at you but you get used to them and just ignore all that)
Once you have the account, I use photobucket, then you can choose from your sight at that account to down/up load a picture.... click on this and a new browser window will appear of your computer files / desk top... you work through this until you find the file and then picture you want to load..
then you load it into your account... then you can name it usually, resize it and such if need be... you can then, as mentioned, choose a 'code' for showing it... it's not the picture you chose but will usually be a pull down menu under the picture that says... HTML Code or IMG code and you copy that text and then paste it into your post here... best to use two windows on your browser. When you hit submit, the picture should show up in your post.