I need a lawyer to do this process.

Go to www.USCIS.gov

Read the instructions for applying GC to your spouse.............

This will take atleast 2 yrs according to the current trend ............

Why did not you ask this question before you went to Nepal and got married.
So far the green card holder who went to nepal and got married they were able get wife and two kids.
I think one more added in my data.

'magorkhe1' bro..
How? I am planning to get married in near future and having GC. Could you please elaborate, how it works?

Pratik:
People with working Visa gets there spouse easily than Green card holder. Green card holder has to await until the get citizenship. During that awaiting period they visit couple times and make baby. I was referring to those people.

Magorkhe:
Topic k ho pada bro
" I am greencard holder of US i got married from Nepal i want to bring my wife from Nepal to US "
Timro reply ki timlai taha cha turantai leraune upaya:
"Why did not you ask this question before you went to Nepal and got married.
So far the green card holder who went to nepal and got married they were able get wife and two kids.
I think one more added in my data. "

Timro 2nd reply:

People with working Visa gets there spouse easily than Green card holder. Green card holder has to await until the get citizenship. During that awaiting period they visit couple times and make baby. I was referring to those people.

Aba timra reply herera bhana ki timlekasari bhanna sakchau ki timllai taha cha GC holder le turuntai leuna paucha bhanera................

If you are GC holder and apply to your Spouse now and submit the required documents on time , it takes around 2 yrs and via citizenship it takes about 6 months in my understanding.

You can hire a lawyer to take care of your application if you are not sure of what to do and what documents are necessary. It should cost anywhere between 1100 - 1500 dollars. But if you are willing then you can take charge of your own application process and it is not that difficult unless your case is complicated like lots of marriages/divorces, unpaid child support etc. But, if you are marrying for the first time and has no kid then do it on your own.
Apply I-130 for your spouse. It is a basic application and you will need your wife's Birth Certificate and the marriage certificate and of course you GC proof. It usually gets approved within 2-3 months. Being a consular processing, your application then gets forwarded to NVC. It remains there until your Priority Date(PD) gets current. Then when it is about to get current, NVC will contact you for the next steps and where and how to pay various fees.
My personal case: PD of Jan, 2016, PD about to being current and waiting to hear from NVC.
No, you don't need to wait for getting your own Citizenship like someone mentioned above. He probably don't know what PD is. I have seen that in around 2013-2014 when F2A dates were all current but now it has a waiting period of 1.5-2 years.
So go ahead and apply I-130 without further delay, even if you get RFE you will get an earlier PD. Just don't delay. But, if you are on the verge of getting your Citizenship then just wait and apply once you get and at that time you can say FCUK Priority Date ;)
Good Luck

Save the headache and get a lawyer. If not....all you're gonna do is read this forum, or hear other nepali people that tells you 500 different thing, or you're gonna google it yourself.....which is gonna confuse you more and more.