How do the people that still practice the old norse religions do it?

Yes there are people that worship the norse gods. The religion is called Asatro/Ásatrú (scandinavian/icelandic spelling), the word is composed of Ása + trú = God + religion.

The religious gatherings are called blót (pronounced like bloat). At a blót people will proclaim their devotion to all the gods and most often pick one or two that they particularly like or need attention from and give them extra praise. Often people will eat well and some will drink alcohol. There is usually a very joyful atmosphere and warmth at a blót. People take much interest in each others lives and try to make everybody feel welcome.

The religion does not in any way require anybody to die in battle. But those that do die in battle while fighting a just cause, will be rewarded by sending them to Valhalla/Valhöll where the gods sit among men, eating & drinking, fighting & singing.
Many modern followers of the religion say that "fighting" for a good cause and "fighting" for a better world until the day you die will also get you into Valhöll, while sitting by while the works of evil people ruin the world will send you to the realm of Hel. But there are also other places you can end up in when you die, such as Fólkvangur, where Freyja rules, or you can end up with the godess Rán if you die at sea. And virgins will end up with the godess Gefjun.