Alien Tech can be fun, your characters don't necessarily have to understand it to use it, so you won't have to worry about all the nitty gritty details. You can just say it's alien and that's all there needs to be to it. Now, that being said you do need to know a few details about alien tech to make it believable.
For starters, is it a type of biotech? Or is it some type of radioactive powered ray gun that works great as long as it stays intact, but if the powercell is damaged in any way it causes a nuclear meltdown equal to the Hiroshima bomb. Or maybe the user just gets a bad case of radiation poisoning that may or may not be cured/curable.
Secondly, do humans have this tech, or is it limited only to the aliens that brought it/created it? If a human can't use the tech due to some biosignature, and your story is past that part, then it would be unreasonable for your hero to forgo his AK-47 for the alien blaster he just confiscated off a fallen enemy.
So even though you can get away with very little when dealing with alien tech, there are a few details that you have to know. Now most of this might be background knowledge that only you will ever see, while only giving your readers the juicy details, but you still need to know it in order to write the story.