Pretty much as the title says, i have an old device running the android version 2.3.6 (ZTE Kis plus).I am not very keen with smartphones and stuff and but i want to have a newer version of android is it possible somehow ?
if ZTE did not push an update for your phone to go from 2.3 to the newer version 4 you will likely have to use a custom rom.
i found one for the lite version of the phone (not the plus version so you will need to find one which is for the plus) this shows how to do it for the lite (not plus) version for information only https/www.youtube.com/watch?v=n_DJhaNH14o
keep in mind that there is a chance that you can brick your phone by using custom roms.
Consult your Mobile manufacture about your phone does have updates to newer versions. Or else go to xda-developers.com and there are a lot of helpful folks who are baking custom roms for devices.
Be aware of all that stuff before proceeding.There is a chance of bricking the device.
it has 800 mhz processor. Which is not good enough for newer versions of android. There's in't much of anroid 3 ROMs. However android 4 ROMs are mostly available for phones. And I think its processor isn't much strong to run well. It will run newer versions but absolutely have low performance with frequent lagging.
Now comes RAM part. I have phone with 512 MB RAM. It mostly uses 200+ MB RAM in 4.0 android version and sometimes more than 300+ MB RAM in 4.1 and 4.2 also sometimes in 4.0 version. Your phone have only 256 MB that is really low in my opinion. However once I flashed 4.0 android ROM on my friends phone HTC wildfire S that comes with android 2.x. I upgraded it to android 4.0.4 and after few days he told me to downgrade back to v2.x.
If there is any custom ROM is available, you can try but make sure you have a backup first. There is chance of bricking. That means your phone wont be usable like a piece of brick. Unbricking is possible but I m not sure about your device. So make a backup and if you found any ROM install it. Please see tutorials for this and I think it will require root than custom recovery and than custom ROM. Trying wont cost anything . Just good luck and do right steps.
EDIT: I saw that plus version have 512 MB RAM. So RAM is OK in your case, Even 4.4 kitkat version can be used in 512 MB RAM phone.
If your phone uses mediatek SoC (system on chip) then you can only update upto 4.2. This chip doesn't support higher than 4.2.2 version, so don't search about more higher. It should run android 4. But finding it online is another headache.
Btw is this phone also called ZTE KIS v788? If yes there is a guide here: http/samsungkitkatjellybeanrom.blogspot.com/2012/11/upgradeupdate-zte-kis-v788-to-android.html
If no then don't try, flashing ROM of other phone causes soft brick, can be solved by restoring backup made from recovery mode.