Here in this guide,
I'll show you how to post pictures in forum as many people just don't know how to do it.
Step 1: Go to http://imageshack.us/
Step 2: Click on the browse button and browse for the picture you want to upload.
Step 3: Click on the upload now button below.
Step 4: After uploading successfully, copy the link that i circled.
Step 5: Just paste the code onto the big box as shown below .