Open up your picture and then go to file and click Save As. Under the box where it asks what you want to save it as theres a drop down menu. Click the arrow and there should be lots of letters listed...BMG, JPG etc...click on the JPG and then click save. Come onto here and in the reply box at the bottom it says "Embed picture in post" Click in the box next to it and then click the underlined "Click here to upload!" This will bring up a box with an option that says Browse. Click the browse button and then it should bring up all saved pictures. Scroll down untill you find yours and double click on it. Then click OK in the box with the browse menu. It should now say File Uploading. If it stops and says file exceeds limit then you need to go back to paint or whatever and scale the picture down. Re-save it under JPG and repeat above steps.

Hope that helps