Here is a simple tutorial for you.
I use tinypic but it isn' t the only choice, just my preference.
Go to Tiny pic by clicking this link:
Tiny Pic
Step 1You will see the following on the screen and you will need to click on the "Browse" button.
Step 2After clicking on the "Browse" button a similar screen will pop up as this:
From there you will need to locate the image you want to upload, select it and click on the open button.
Step 3You will then need to click on the "Upload" button as shown below. When the Screen changes the file will be uploaded.
Step 4All you need to do now is copy the link from the box that says:
IMG Code for Forums & Message Boards and post it into your Message Board Thread