How many pounds of muscle can you gain?
 

I am just starting to lift and I was wondering what a goal I should have for myself for 3 months? How many pounds of muscle can I gain in these 3 months, or should I set for a realistic goal? Like I said I just started. I do not have a routine in place yet, so any advice you can give me is great. I am 26 years old, 215 pounds and am 5'9".

It depends. I would not focus on what the scale says, rather on what weight you have on the bar and set goals for that in 3 months. As a raw beginner, you can add alot to your bench/squat and deadlift in that time. If you get stronger, you will get bigger, especially as a beginner you can se great results the first year and also build a good base.

In three months?...Not a lot.
In three years?...Quite a bit.

If you've never lifted before, you can see some great results in 3 months. To get real appreciable mass gains it will take a while longer, but you (and others) should notice a difference in your appearance after 90 days of dedicated training.

As to a routine, I like full body routines, 3-4 times a week. My basic set up is

Squat
Bench
Row

Deadlift
Over head Press
Arms

Bench
Squat
Row

Power Clean
Deadlift (from raised blocks or a rack)
Over Head Press

It isn't real fancy, but its helped me get a lot stronger very quickly. Starting out, maybe drop the 4th day and see how it goes. Focus on your form, and once your form is solid, add weight to the bar when you can, in relatively small increments (5-10 pounds per session).

this.

In three months time you will not see that huge of a difference I am sure. Keep up the hard work and you will see results and get bigger like you have stated before that you want to.