Formatting proprietary Twitter file properly

[CowCookie]

The Twitter monitoring tool my employer uses doesn't export Twitter metadata, so I had to do a crude workaround in Excel to extract the original Twitter users and who retweeted them. The result is a spreadsheet with the following columns:

Issue_Date|LanguageCode|Headline (tweet text)|Twitter user|OriginalURL|Twitter Followers|Twitter Following|Retweeted

Twitter user is the account that made a tweet, and retweeted is the person they retweeted if the tweet happened to be a retweet. (About half the rows have a blank retweeted cell because they're original tweets, not retweets.)

I know I need a source and a target, but would anyone be able to tell me what column should be the source and what should be the target?

Also, I'd like the graph be directed, so should I just insert a Type column and label all cells in that column as directed?

Thanks in advance for the help. I've read the various tutorials and searched on the forum for Twitter information but haven't found anything about this yet.