2.92Mb is (basically) 2920 K... in other words, WAY over the size limit.
Microsoft's Photo Gallery program can help you resize them.
After installing it, if you don't already have it, you'll probably have to import your pictures to it's library.
After that, just right click on a picture and choose "Resize", set the largest dimension to "640" and you will
generally end up with a picture that fits the forum perfectly but also fits the size limits.
Otherwise, you can set up a free photobucket account, upload your images to there and link to them in your posts, by copying their URL, clicking the
button in your reply and pasting the URL into the popup box.
The downside there is that photobucket doesn't resize them, so they may be too large to fit well on a forum post.