I need to know how to hook up the lexmark x5150 printer to my computer i have no manual.

Computer on, Windows running, Lexmark printer NOT plugged into the computer, via the USB cable.
(Lexmark X5150 off, and unplugged from power)

There is an Installation CD that comes with the Lexmark. (If you do not have this CD, please come back, and state so)
Open your optical drive, (CD/DVD drive), insert the CD.
Follow the instructions for installing the contents of this CD.

After the software has been installed, you may be instructed to restart your computer,
(Start>Turn Off Computer>Restart)
If not, do so at this time.

After Windows has fully loaded again, plug the USB cable from printer into the computer. (You can use any available USB port on the computer. Doesn't matter which one)
Now plug the Lexmark into power. (Surge protector)

Wait to see if the Lexmark has to set itself up.
(20 to 30 seconds)
Now press the Power On button for the Lexmark. Hold it down for 2 seconds.

You should now see a pop-up out of your system tray. (Bottom of monitor screen)
"Found New Hardware", and perhaps a second one after that, "Found Lexmark X5150"

Do NOT plug the Lexmark into the computer (Via the USB cable), until the software has been installed First! (Installation CD)

Lexmark indicates plugging the printer into power, attaching the USB cable from printer to computer, then installing the Installation CD.
I would advise against that.

When you attach a device to a computer with Windows, Windows automatically tries to find the drivers for the device. (Software) If THE drivers are not installed yet, Windows will try to match up one of it's Generic drivers. This will Not work.

This is Lexmark Support, and the page specifically for the Lexmark X5150 (Your Lexmark X5150 is part of the X5100 Series)

http://support.lexmark.com/index?page=answers&startover=y&question=lexmark+x5150+user+guide&locale=EN&productCode=LEXMARK_X5150&segment=DOWNLOAD&userlocale=US_EN#1

Click on the -> Publications, tab.
[Answers, Top Documents, Publications, Downloads)

In red you will see two titles. One is the Setup Guide, and the other is the Users Guide.
I would choose Users Guide. [It has the setup information in it also]

After you click on -> X5150 All-In-One Series User's Guide, (in red), you may not see anything happening for a few seconds. This is a PDF file, and it takes a few seconds to see the first page. It's downloading. Let it download all the way before looking through it.
You can also save a copy to your computer.

After the PDF file has downloaded, go up to the top header, and click on the Floppy Disk icon. It is the second icon from the left. Hovering your mouse cursor on it will briefly reveal, "Click to save this file to your computer or another location"

With the computer running, plug in the printer connection wire into a USB port. Then turn on the printer. If you're lucky, the computer will tell you it just found new hardware and after a few minutes...2 or 3...will say it's ready to use. If not, it will tell you to install the CD that came with your printer. Then follow the screen prompts. The minimum required is a "driver". Much of the other software on the CD is for photo manipulation or other functions that you may or may not want to do so yo might ignore adding the extra software. Just read the screen for details to decide if you want to install it. Or if you have room on your drive, just install everything and not have to install anything in the future if your needs change.