Data Series is a list of dates and their associated values. Importing your own data series is easy:
Click on Research→Imported Data Series then New → Data Series.
Select the file from your hard drive (CSV). First column is the date, second the value.
Select the Date Format from the dropdown. For example yyyy-mm-dd.
Select other options like the decimal format and whether a header row exists.
Click upload. If there are errors they will be reported including where they occur.
Click the Save icon indicated by the arrow.
Verify your series by clicking on the Chart tab.
Below is the result of uploading a series for a file called IBM_close.csv.

Adding/Updating Your Series
To add or update data click on the series and select the file with the new data. You can choose what happens to the existing data from the Existing Data dropdown:
Overwrite will update values on the same date
Skip will skip the values on the same date
Delete will delete all existing data first, then add the new data
Using Your Series
Imported Series can be used in formulas of all the main components like Ranking Systems, Screens, and Portfolio Strategies using the GetSeries("series name") function.
So, for example, let’s say you only want to check if the FRED data for the US leading index is 0.5% or higher. One way to do this would be to upload the USSLIND data from FRED in a series with the same name. Then in a rule, you can check like this:
Close( 0, GetSeries("USSLIND") ) > 0.5
Or if you want to know if USSLIND is above it's SMA(10) you would write:
Close( 0, GetSeries("USSLIND") ) > SMA( 10, GetSeries("USSLIND") )