You should get some horticulture design's pics for selecting.
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Cut the secondary trunk off back to the main trunk. Remove branches annually (best done during dormant season... now) to 50% of tree height as the tree grows (when they're small so it's easier to do and it re-directs growth to the top... rather than into the unwanted trunk and branches.) To straighten it out, stake and guy this tree now (while it's young and flexible.)

Looks like the little tree behind needs some of the same attention.

Others will probably tell you, too...Silver Maple is not considered a very desirable tree as it has some bad habits. Hopefully you don't need a refined appearance down the road as it can become quite scruffy looking. It will look decent during its youth and teenage years, then begin to acquire a lot of dead wood. The wood is weak, too.

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There is a very active Tree Forum here on GardenWeb. You should also post your question there for a 'second opinion' if you want more thoughts beyond Yardvaark's excellent advice written above.