If the beam is twisted you'll have to work with as is. If it is tilted you can stand it up straight. You will need four pier blocks preferably with saddle bracket, two ten foot 4x4's, pressure treated, and two bottle jacks. And most important, a skill saw, tape measure, big sledge hammer, and some 3-4" screws.
Now get all that crap under the house and try this. Place a 4x4 up next to beam at one end on the side you need to move it toward, and screw it up with one screw at each end to hold it. Now place a pier block one foot in from each end. Measure the height between pier and 4x4, the pier should be on clean flat raked ground with no loose dirt, add 3/4 of an inch to this and cut a post, (you will shorten these more later and use them as perminent posts). Now jack next to block at both ends evenly about 1/2 inch, then pound in posts. Repeat this at other end of beam.
Now a great deal of load has been removed from beam. Go to each end and hit it until it stands up straight, then remove your temporary posts. Then remove 4x4's. Now place the pier blocks evenly spaced under beam, again on flat clean hard ground. Measure to beam and cut 1/4 inch longer this time. Jack beam slightly, and pound posts in place starting from one end, (if the ends are resting on foundation, place first post a few feet away). After all four posts are in place, go up and get a cold one. This is the time to go through house and check all the doors and windows to make sure they aren't bound or rubbing. If they are, you will need to shorten some posts, but not likely.
Now you can return to the pit and place one screw in each direction at an upward angle through post into beam bottom. Then secure to bracket in pier with one on each side. After this you have completed your job. Good work, have another cold one. Good luck.........