You are off to a good start because you got two. They'll will gain quicker with company.
You will probably get a lot of different suggestions because everyone does it differently. The good thing, you really will have a hard time messing up as long as the steers aren't crazy.
I would suggest picking a target weight - lots of people like 1200 lbs. - and put the last 300 lbs on them with full feed and corn. Theres nothing wrong with letting them eat good grass but I prefer grain to finish.
What I do is pen them up when they are around 300 lbs off target and give them free choice hay and peanut hulls and corn gluten mix. I gradually get them to free choice on the feed and the last 45-90 days change this to straight corn to fatten and get the fat color right. I then slaughter when they are "finished".
The length of time it takes to finish one will depend on the breed and frame size of the animal.
Good Luck.