Lirpa

Yes, I saw it online , I will have to fill out a form 134 I believe, it's a affidavit of support .

I have an i-130 spouse petition pending , i recently gave interview and got b1/b2 multiple entry visa.. 
 
I am no expert but from what all i learned from endless reading through forums...
1. the last thing you want to do is to file a support for her, since the more means she declares as supporting herself the more VO gets convinced about her ties back home. You filling for a letter of support for her actually might hurt the case as it shows if she decides not to return then someone will take care of her. My advise if and when asked on ds or in interview please declare self support. 
2. VO most likely wont ask to show any documents as mostly all VO's are trained to take decidion on basis of past travel history, criminal record, current status and THE INTERVIEW! PLEASE DECLARE EVERYTHING 100% ERROR FREE IN DS-160.  
3. while fillinf ds-160 please make sure to present an exact travel plan.. (remember you can make changes to the travel plan) but having a precise reason/purpose to travel and an exact plan shows VO that the person has ties back home so the had to plan the trip. 
 
Good luck !

Yes, I saw it online , I will have to fill out a form 134 I believe, it's a affidavit of support .

There is no such thing as sponsorship for a tourist visa.

From what you have posted there is a very low chance of her getting a B2 visa. Way too much of an overstay risk.

Best to let her pay her own way.

There is nothing you can do to “help” her get a tourist visa. The only thing you can do to “help” is help her with the forms if her computer skills or literacy skills are lacking. No letters, promises, pictures, phone calls, emails from you to anyone will make any difference. The case will be decided on her merits alone. 
 
It’s nice of you to offer to pay for things for your sister but this may hinder her case more than you realize. 

Very little chance. Consider meeting in a 3rd country