You need a channel to invite people from. By far the most effective channel is your own email list. If you have an email list, send the test link along with your ask and compensation details to the list.
Other options could be your social media handles or social media groups you're a part of (Facebook groups, Slack channels, etc).
Note: don't spam third-party communities. It won't work and only hurts your reputation.
If you don't have a warm audience to tap into, you're likely not able to recruit the panel in a timely fashion. You should then use Wynter's premium audiences instead, and get results in 12-48 hours.
Typically you need to invite 3x as many people to participate in the test as you need panelists. So if you need a panel of 15 people, invite at least 45.
People are offering up their time to help you, so you likely need to compensate them for their time.
If you have a massive fan base, you could get panelists for free because they love you AND you have a big email list. If you don't have those things, you likely need some sort of compensation.
Typical options are either free products (depends on the business you're in, e.g. can offer a free month if you're a SaaS business), gift cards (e.g. Amazon), or cash (via Paypal).
How much to pay depends on how much time you're asking for. This should be a fair trade. A typical test takes 5-15 minutes to complete. What is their hourly rate?
We most often see payments in the range of $15-$50 per panelist (the more senior they are, the more you need to offer).