I need help installing a new ROM on my android?

Yes, I do it all the time.

First, check to see if there are any alternative roms that were built for the MT3g-fender. That wasn’t the most popular of phones and its about 3 years old, so there may not be much to choose from. In any event, read this: http://forum.xda-developers.com/showthread.php?t=734617

If you haven’t already done so, install a new recovery image (usually recovery.img) on the phone. Clockwork Mod is well known and may well be the one for you. There are others, but mostly for newer phones.

Once you have the new recovery, then decide on the new ROM. Go into recovery mode and tell it to install the new ROM.

You have some homework to do, but this can be done.

I am a fan of CyanogenMod myself, and run it on my old Droid X as well as a Nook Color. Sadly, CM doesn’t appear to have a version for the myTouch Fender; apparently it wasn’t popular enough to warrant one. The myTouch Slide has a version of CM available though, and there is always the possibility of a version that will be close enough but unsupported.

ClockworkMod is an awesome tool though, and no matter which ROM you go with, you will probably wind up using ClockworkMod to install it.

Even without installing a new ROM, you can still install arbitrary apps via “side-loading”. I have the Android SDK installed, so I use the “adb install” command to do this.

You can also install ROMs using “fastboot” (it also comes with the SDK) if for some reason the recovery doesn’t work.

well, see I am having trouble doing that. can anyone explain how to do that?

Maybe, if you explain what you mean by “that”.

Do you mean side-loading?
Do you mean fastboot?
Do you mean installing CMR?
Do you mean using CMR to install a new ROM?
or something else?

Installing cmr and a rom

Then you need to read the material linked in @elbanditoroso‘s post.
That will give you the information you need to get started. Since you’ve already rooted the phone you need to set up the SDK. That will give you flashboot, adb, and other tools you need in order to continue.

If you aren’t sure what you are doing, read all the documentation at developer.android.com and the relevant threads on xda-developers.com. If you flash your device without knowing what you are doing you can easily ruin that device.

Ok, thank you

ok, the documentation on the developer android site, im not quite sure where your directing me on there. Same thing goes for the xda website. Thanks man

I think @rexacoracofalipitorius is directing you to the entire documentation. Flashing ROMs isn’t exactly simple, at least not if you lack the decades of computer expertise he and I have.

Well I have 10 years of computer experience.. i just have never rooted a phone before.

I’ve been doing computers for for over 30 years, and rooting my Nook Color still required a considerable amount of reading to familiarize myself with the quirks of Clockwork, CyanogenMod, and Android well enough to get it right on the third try.

I probably should have said “especially”, instead of “at least”....

First step is to install the SDK, linked above.
Read the docs for adb and fastboot. You will need those tools.
After you have done that you can think about installing ROMs- or you can use “adb install” to install apk’s. Usual caveats apply. IIRC “adb install” is not covered in the regular docs, you may need to google it to find out how it works.

Once you have all that taken care of you will need to review the particular documentation for the specific ROM image you want to install. They aren’t all the same.

This is as close to step-by-step instructions as it’s possible to give here, unless someone shows up with an identical device who has done the identical process. You’re on your own (or rather, you’re in the hands of xda-devs and the other relevant forums) now.