In Telegram, find the New Group button in the toggle menu at the top-left screen corner. Select at least one group member to add from your contact list (you can add @InviteMemberBot, aka InviteMember) and hit Next.
Now you can enter your group's name and set your group's photo (if you don't have a logo, you can get a free photo/icon from websites like unsplash.io and iconfinder.com).
When you're ready, click Create.
After you've created your group, you can follow this guide that explains how to add a group to your InviteMember project.