If your having trouble with plants you buy then you have some fundamentals wrong and just need to keep reading here on T-ville. It can be overwhelming to start growing tomatoes, etc. if you've never grown anything but that's how I started as well. Keep reading and watch youtube videos and you'll get the hang of it.
That's a really vague question but I think alot of people including myself probably started with some type of dome/greenhouse like below...
https://www.ebay.com/i/263528738735?rt=nc
It's really quite simple if you follow the directions! You can go wrong though by watering too much or too little (like Worth said) and putting the seeds too far down in the pods.
Al