i use photobucket to upload my photo's of my pc it is free to use, when the photo is uploaded and in your photo album you can move your cursor over a image and it will give you four options for you to share your pic
Email & IM
Direct link
HTML code
IMG code
click on the word direct link and the image code at the side will say copied once you have done this you can then add the pic to a new thread or a reply to a thread on the forum,
when you open a thread or reply to a thread you will see icon's above the box where you enter your text, when you hover your cursor over one it will tell you what each icon represents you need the icon that looks like a small picture, once you have found it click on insert image and then right click and paste of press ctrl v on the keypad and the image code you copied from photobucket will be inserted in to the text box where you will be able to move the text,
then before you post do a preview post and when you are happy then post on the forum, you can always come back and edit a previous post,