After creating roadmap you can start working with it

View by: You can choose the view by Week, Month or Quater
Add: Add lane or milestone, you can directly add on the board
Issues box: Open issues box to search and drag& drop into the roadmap
Settings
Adding lane
Use menu bar or click on the roadmap to add lane

Once created you can edit the title, color , delete lane or move its position

Adding issues
Open the issues box from Menu bar, search for the issue and drag into the board

Or click the white space on the board to open the dialog

Pick an issue or create a new one to plan

Adding milestone
Use the menu bar or click on the timeline to create a milestone

Enter the name, change the color or date then Save