In the desktop application, you will start by opening the tab at the top left called File.

Then you will need to click on Open & Export and click Import/Export.

You will be prompted to select a file type and you want to select import from another program or file and click Next.

From there, you will have 2 options, you can use comma separated values(.csv) or Outlook Data file(.pst). Outlook Data files are generally if you are importing a contact list that is shared with you in Outlook. Comma separated values are the excel files that are imported into Outlook. For this example, I have created a contact list in Excel and saved it as a .csv file in order for it to be imported so I select comma separated values then click Next.

From there, you are going to be prompted to select the file to import. You would click Browse and find the file containing the contacts you wish to import. The options that are given are personal preference as to whether or not you want to allow duplicates to be made if the contacts already exist, replace the existing contacts with the imported list, or skip the duplicates. Select your preference and click Next.

After that, you should be prompted to select a destination folder. You want this to be imported to Contacts so you select that folder and click Next.

Once you click next you will be prompted to verify and finish. There is an option to map custom fields which is useful if you have issues with Outlook being able to match up the information in the Excel file to the Contact information. For example, if you use Business email instead of email address, outlook might not recognize that heading for that column in the file. You can map each individual column to where you want the information placed in the contact profile. When you are done with this step click on Finish and it will import these contacts into your contacts.

This will import all your contacts into your contact list in Outlook. From there you want to go to your contacts and click on New Contact Group.

Put in the Name of the group in the Name section and click on Add Members at the top and go to From Outlook Contacts.

Here you should have a full list of contacts from your Outlook profile. You can either select each contact individually from the list, Ctrl+click each one you want to add, or you can click on the top of the list and scroll to the bottom and Shift+Click will select the whole list and you can click Members when you are done selecting the ones you want to add.

This will compile the whole list for you and when you click OK, it will add this contact group into outlook so when you want to send a message to everyone in this group, you can just type in the title of the group and send it to all of them.