This will be a challenge. This puppy is too young to be taken away from it's mother. There are reasons breeders don't separate puppies from their parents until 8 weeks of age. I realize that most people think that at 7 weeks it's not that big a deal, it's only a week. But consider how much that puppy has grown in those 7 weeks, from a newborn that could only nurse, to a pup that eats solid food. One week does make all the difference. But, it is what it is.
First, you'll have to find out what food the puppy has been eating. Do not abruptly change foods, it will cause your puppy to have diarrhea, even vomiting. If you decide to change foods you'll have to do it slowly. 1/4 new food and 3/4 old food for a few days, then 1/2 new and 1/2 old for a few days, then 3/4 new and 1/4 old for a few days, then all new. If the puppy shows any signs of not accepting the new food, wait a few more days between.
You may have to wet down the food he eats, as he is still a very young baby. He may not be able to handle solid foods yet.
Make sure to get a vet check immediately. He should already have his first set of shots and de-worming. If he hasn't, then you need to book that immediately. He will need three boosters in his first few months of life.
Crate training will be easier, for most breeds, at this age. Make sure that the crate is in your room, and that it has a comfy dog bed that can't easily be ripped apart. Puppies will chew and eat anything in front of them.
When crate training, one thing to keep in mind. A puppy can only spend so much time in a crate during the day. The rule is, 1 hour per month of age. In other words, at 7 weeks, your puppy should not be crated during the day for more than 2 hours without relief. A puppy cannot hold it for longer than that amount of time. During the night he will need to relieve himself. He's a newborn. If you have kids, you know how often they wake up at night to feed, or have a diaper change. Unlike a baby, your puppy should not feed during the night, but he will have to relieve himself. Most dogs won't pee or poo in their crate, if it's the right size.
Having said that. A crate should be large enough for your pup to lie down, turn around, and stretch out. Bigger isn't better when it comes to a crate, so you may have to get a new one when your pup grows. I highly recommend crate training. Puppies chew on everything. If you have to be out of the home, having your puppy crate trained will ensure that he's safe while you're gone. I have a 3 month old puppy at home right now, brought him home at 8 weeks. Crate training has been so very easy with him. I wish I could say that about my other dogs. All except one of my dogs were crate trained. The only one I gave up on was our beagle. The others were crated, but they weren't as easy as our newest fur baby. It takes time. The first night is usually the hardest. Puppy will cry, and you will be tempted to take him out of the crate and bring him to bed. Don't do it. I now sleep with my beagle every night because I gave up. The others, I stuck it out. But then, they didn't manage to get out of the crate like my beagle did. ;)
When going for walks, wait until he's had his first booster. After that booster, only walk in your neighborhood, on the sidewalk. Parvo is the main concern, and he won't be fully immunized against Parvo until all his boosters are done.
Training begins immediately. The biggest challenges will be biting (puppies bite because they're teething, and they simply don't know better). The technique I use is the "yike" technique. Puppy bites, you yike like a puppy, then walk away and ignore him. As he gets older you can substitute the yike for a firm no.
Potty training won't happen overnight. Take puppy outside every hour for a pee. Choose a potty word like "potty time". When you take pup outside say "potty time" over and over. When he potties, tons of praise, even a treat. Let him know that this is what you want him to do.
If he potties inside, a firm no, then take him outside. If you catch him mid pee, or poo, simply pick him up and take him out. No punishment. Remember, he's a dog, and he has to learn to live with his humans.
I don't know what else to cover. Do you have any concerns?
I'm very willing to help with any concerns you have. This service is free, but I do have a fee. Pictures! I'd love to see this new fur baby. :)