All the contacts you import, will automatically go to "all subscribers". To segment contacts to different lists, you need to give all your contacts defined parameters.
Preparing the contact file
Open your contact file in Excel (or other similar program), make sure you have all the emails in one column and the title of the email column should be "email". Add a new parameter in new column, e.g we would like to create press list - new parameter can be "press". Add values to all the contacts in the parameter column - "yes"/"member"/etc.
You can add as many parameters as you like - birthday, language, sex, country or business_clients, press, schools etc. Depending on what lists you would like to create. Email and birthday are system fields, but all others you add in the file are extra parameters that can be used in creating filters. See more in our importing subscribers manual for more information.
When parameters are added, save the file and import it to the account. You can create a filter while importing or later by clicking "create a filter".
When the importing is completed open the new list and change the segmentation rules. Choose from drop down menu the new parameter you added (1) ("press") and insert in the field (2) the value you gave all the contacts ("yes"). Click on "save changes" to finish creating the new list.
Created list is now parameter based and you can add more contacts to this list in the future, using the same parameter and value.
Here is also a video tutorial: