If you want to quickly filter based on a list of IDs (for example, listed in an Excel spreadsheet column), you can just copy and paste the column of numbers directly into the Contact Filter ID field. The numbers will appear each separated by a new line, which works just as effectively as comma-separated values.
However, if you particularly want to convert the list into IDs separated by commas, here's the process:
Copy the column of ID numbers
Open a new Word document and right-click, then select paste “Keep Text Only”
Use the Find and Replace tool in Microsoft Word to find "^p" [paragraph mark] and replace with a comma.
In EventsAir, select Filter
Paste the list of ID numbers, separated by commas, into the ID field
You can filter to include all these ID number records OR, by clicking the gray strikethrough symbol on the right, you can exclude all these records.