Salmon goes well with dill sauce (such as in this recipe). It also goes well with sauces that includes fresh herbs, lemon, honey, garlic, soy sauce, mustard and Cajun flavors.
There are many vegetables that would go well with your Salmon as a side dish. This includes vegetables like roasted asparagus or maple-glazed brussels sprouts.
Ways you can tell it is done cooking:
Usually you would be able to tell by that your fish done cooking because it would be able to flake easily using a fork and the flesh of this fish is opaque. Here is a further link you can click on to learn more about cooking salmon.