When you join an affiliate program, you get a unique tracking link. This link contains an identifier tied to your account. When someone clicks it and makes a purchase, the sale is credited to you.
Commission rates vary by product and network. Most digital product commissions are higher than physical product commissions because there are no manufacturing or shipping costs involved. Cookie duration is another important detail to check before you promote an offer. It determines how long after a click a sale still counts as yours.
Payment schedules also differ. Some networks pay weekly, others biweekly or monthly, and most have a minimum payout threshold. Read a product's affiliate terms before you promote it to avoid confusion later.
Some affiliate tools on the market are built specifically to help you track clicks and commissions across multiple offers in one place, which is worth looking into once you are juggling more than one program.
Before you promote anything: find your unique affiliate link in your network dashboard. Confirm the cookie duration and payout threshold for that specific offer. A tool that brings your links and reports together can make this easier once you are tracking more than one program.