Go through the following steps to add a group:
1. Click on the Add group option in the top left corner.
2. Type the group name you wish to choose and press ENTER.
3. You may also add contacts individually by filling in the details or by directly importing a CSV file of your stored contacts by click on Send custom SMS and Browse your .CSV file.
Also, there is no limit on importing contacts.You may import any number of contacts in one go.
NOTE: The only restriction is that the file size should be limited to 32MB.