is there a way to put pictures together too create your own background for twitter?

[selina_555]

A "colash"??? That is so cute...... I guess you mean collage?

If you type the words "free collage maker" into a Google searchbox, you will instantly get many hits, just like this:  http://bit.ly/wR1AHO

Here are a few examples:
http://www.photocollage.net/
http://www.photovisi.com/
http://www.kizoa.com/
http://photobucket.com/

Using a website is fine if you only want to make one collage, but if you do it regularly, you end up having to upload and then download again a whole bunch of photos. If your internet is down, you have nothing.
Also, resident programs are usually much better than free websites.

So in my opinion, you are better off with a resident program on your computer.
Again a simple Google search will give you plenty of options.

The best collage maker by far is this one: http://site.lumapix.com/