I'm not using redhat, but I've tried this in several different distros, and it seems to work: If you set both terinals up on the same work-space you should be able to use alt+tab to switdh between them.
There are two ways to mark and paste. First, and most simple, just use your mouse to highlight the area you want to paste into the other terminal. Then alt+tab to the other terminal, place the cursor (using the arrow keys) where you want to start the paste procedure, and click the middle button on your mouse. It should paste exactly starting where your cursor was. (In some systems, or programs you can move the cursor with the mouse. If yours is that way, then you can place the cursor with a right click, and paste with a middle click, but you must be sure to do the middle click right after (next to) the cursor placement, or you will have moved the cursor and pasted in the wrong location.
If "cut" and paste is what you wanted, you will have to go back to the original terminal, and delete the portion you wanted cut. The above paragraph only describes the copy and paste procedure.
The second way you might prefer. If you are used to using Ctrl+C to copy, and Ctrl+V to paste, upi can do the same thing in a terminal, but the difference is that you do not use the control key alone, but rather with the shift key. In otherwords: Ctrl and Shift + C gets you the dopy, and Ctrl and shift + V gets you the paste.
offhand I can't ell you if the Ctrl and shift + x will get you the "cut" action or not.