If you would like to add a web developer/designer to your website so that they can make amendments to your site then you will most likely need to set them as an admin.
You should always backup your website before you do this so that you have something you can go back to if the worst happens.
If you are looking to add someone so that they can publish posts/blogs then you will likely only need to set them as an editor user.
To add new users, you can do either of the following.
Add a user manually via your WordPress dashboard.
- Log in to your website. This will usually be yourdomain/wp-admin
- On the left menu, hover over Users and then click add new.
- Fill out the details on this page and be sure to set a strong password. You can use https://passwordsgenerator.net to generate a strong password (all usernames and passwords are case sensitive).
- Select the user level you would like. If you add admin then the user will have the ability to add and delete users and do everything on the site that you can. Make sure that you are comfortable doing this and if you are working with a web design agency then you should have a contract or agreement in place.
You can alternately use a plugin to do this. This is perfect if you need to give access to a plugin developer or company that can help with an issue you have.
You can download the plugin Temporary Login Without Password either from https://en-gb.wordpress.org/plugins/temporary-login-without-password/ or via the add new plugin page on your website.
When you have done this then you can add a temporary link that you can share. You can set the user level and the time that they have access to the site.