The link tells you step by step how to do an introduction. You cannot simply put the second guinea pig in with the first, or they will fight. You have to follow the instructions on that page, including cleaning both cages, and making sure they have enough cage space.
The vet needs to examine your guinea pig with the hurt leg and see if she's ready to meet a new friend.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry