There are several ways to direct your members to log in to Community.
Info Hub: the "Open Community" Link
The first is to enable the "Show Community Option in Info Hub" option in the list that is synced to Community. This will display a Community icon next to the synced list in the Lists/Committees area of the member's My Info section of the Info Hub.
Info Hub: Navigation Link
With the ability to add custom links to your Info Hub navigation, you can create a link to your Community site (you can find this link in Setup -> Integrations -> Community) for your members that doesn't require them to open their My Info tabs.
General Link to Community
By using the URL to your Community site (you can find this link in Setup -> Integrations -> Community), you can add this link to your website, to emails, to your email signature- anywhere you can add a URL. This link will bring anyone to the Community login, where they can enter their Info Hub username and password to access the Community site for your members.
If the member has not set up their Info Hub login account, they can use the "Create an Account" link to set up their login, then can click the link to Community again to log in.