U dont need to start and account with them. I dont have an account with them and i use imgur.
Step 1: http://imgur.com/
Step 2: Click on blue tab in top left page saying "upload images"
Step 3: Pick and option, be it drag & drop, browse your computer, paste from clipboard or enter image url. Most pick browse your computer I think you should too since ss is in there.
Step 4: Pick your images and upload.
Step 5: After upload they will show preview of images uploaded, right click each image and click copy image, then paste in forum reply box...link will show the image. Then, you post and bob's ur uncle....just like that its done.