Hi @melneumann,
- Add the link for social Menu(Use Custom Link to create this menu)
- In custom link, add full link of social profile (Ex: https://www.facebook.com/username)
- Add the menu and follow the same steps for other social links like twitter, Instagram, etc.
- Select the Social Menu for this.
- Click on Save & Publish to save the changes.
You can check following screenshot for reference.
![Social Menu Setting](https://promenadethemes.com/documentation/wp-content/uploads/2017/06/social-menus-all.png)
Once you set social menu you can assign it to top header from Appearance >> Customize >> Theme Options >> Header Options
For sidebar please go to Appearance >> Widget and Blog Way: Social widget to sidebar.
Thanks.