In order to crop, resize, or edit your picture in anyway, the best thing to do is use a picture/photo editing software. Some recommended programs are Irfanview (free picture editing software), Adobe Photoshop or even Microsoft Paint (if you're a PC user - this is already preinstalled with windows.)  Here is a short tutorial in how to do that on Microsoft Paint.

RESIZING WITH PAINT

To resize using Microsoft paint, first open your image, then click "Image" in the menu bar. Select Stretch/Skew.

There you can reduce the size of the picture by reducing the vertical AND horizontal percentage of the Stretch attributes.

CHANGING THE PICTURE ORIENTATION

Open your picture in Microsoft paint - and then click Image - then Flip/Rotate. Once you're done - save your changes and you're all set!

Just as a reminder, Xanga servers only accepts profile pic jpegs up to 1mb in size, and other image files up to 50kb. So when you resize, make sure they stay under those restrictions. To check the size of your file, after you modified it and saved it, find the picture file you want to upload on your computer, right click it - go to Properties and the size of the file will be shown.