The Top Affiliate Marketing Networks
Affiliate Marketing Networks are the big websites that manage affiliate marketing partnerships. These are open to the public and you can find a variety of affiliate products to sell in all of the major niches and some subniches.
Affiliate Marketing Networks are the easiest and quickest way to get setup to market affiliate products. Affiliate companies are great for training and they will teach you everything you need to know. But the first place you go to find your affiliate products to sell is an affiliate network.
There are quite a few, but I am listing here only the best and nothing proprietary like Amazon or Walmart. Those are networks only "sort of". They are really ecommerce megamarkets that allow you to earn a pittance to promote their products. Go to a real affiliate network and earn more.
To get into affiliate marketing there are a few details you need to work out first before you pick products to sell. You really don't want to go picking products willy-nilly. You'll just waste your time and effort. Read "Affiliate Marketing for Beginners: How to Start Making Money (2022)" if you haven't already. Then when you have done all of that, choose a network and find some products to promote.
It takes time - a little - but still, it adds up, when you have to fill out an application, provide your business, tax, contact, and payment processor info to become an affiliate for a program. That is why it is so much faster and easier to apply to an Affiliate Network. You only have to provide all of that information once, to the network, and then choose your products.
Sometimes seller companies in a network will have some questions for you and they are selective about who they let promote their products. When you are starting out, just skip these. Clickbank is the best place to start because most of the sellers allow you to sell - just pick a product you like and get your link.

AWIN
Awin is the largest global affiliate network. When you sign up for an account you'll have to wait for approval. On top of that you'll have to apply to each product vendor's program separately and get approval for each.

SHAREASALE
In addition to signing up with Share-a-Sale, you also have to signup and get accepted by every vendor of every product you want to sell separately.
Never the less, it is worth taking a look as it has a wide array of vendors which are quite different than what you find on Clickbank. Each to his own.

CLICKBANK
Clickbank is an institution amongst Affiliate Networks. The network boasts volume, variety, and quality of products, and is focused on the digital product arena.You can sign up and start selling right away.
This network has a solid reputation for good business practices, good relationships with its affiliates and vendors, and carrying quality products. Clickbank (CB for short) access is free and it's the easiest to use network.
Clickbank also offers paid online video and text training through Clickbank Spark for a monthly membership fee.
Most Affiliate Marketers have accounts with multiple networks. Start by creating an account with each of the affiliate networks listed above. That gives you plenty of variety and access to lots of products.
You don't need too many products, but you want to find products in the same niche that compliment one another, that you like and feel positive about promoting.
When you start looking you'll find it can be a lot of fun - like going on a shopping spree. So happy shopping - enjoy!