Mark, it looks like a Pistacia chinensis (Chinese pistache), which is grown for that incredible fall color. It's kind of a gawky tree when young, and structural pruning is often needed for it to develop an attractive shape. Pruning deciduous trees is generally done after the tree leafs out in spring; you'll get a much more vigorous regrowth if you prune when the tree is dormant (or entering dormancy, like now). You seem not to be talking about structural pruning, though - sounds like you want to reduce the width of the tree? That is generally not advisable unless you simply want to nip back a few branches slightly. The more you keep cutting it back the more it will just respond with regrowth, most of which will be unattractive water sprouts. If it is really too big for the spot you might be better off removing it and planting something else, or replanting a Pistachia in a spot that is more suited to its size and growth habits.
You could check in with your local Master Gardeners to see if they have any thoughts, or, if this tree is an important part of your landscape, consult a licensed arborist. Pruning trees requires more knowledge and experience than does pruning shrubs or perennials.

Good luck!

Sara

Here is a link that might be useful: Sacramento Master Gardeners

Hi Sara

I like the tree where it is.
I just want to shape it, because there is no shape right now.
As you can see, the branches are all over the place..

Yeah, that's kind of its form...you can try gently shaping once it leafs out next spring (I know, annoying as it is much harder to see the branches when it is in leaf), or work with an arborist - more expensive but likely only need one visit, especially if you pay attention and take notes so that you can do follow up maintenance.

See link for a good summary of the tree from the University of Florida, which specifically addresses the pruning issues.

Sara

Here is a link that might be useful: Chinese pistache

This is one of the most beautiful landscape trees we have, and if it is not planted where it will be able to grow to its potential it will be a shame. It would probably cost a hundred dollars to have a ISA certified arborist come to your house, but worth every penny. Al

Here are the op's photos:

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I would also suggest having a trained professional come out and shape it for you. This is not a huge or rapidly growing tree, so it's worth paying a really good tree trimmer to shape it for you while it is younger. You may not need it touched again for quite a few years.

I was pleased to see your tree sited where it can grow to maturity and be a specimen tree for the whole block. Proper pruning now by a real arborist will go a long way to that end. Al

I also recommend hiring a certified arborist. As noted, you absolutely do not want to prune it until after it leafs out in the spring. It will take a disproportionate amount of careful pruning to correct the resulting overgrowth.

Ryan