For external threads on pipes or nipples, you create the threads using the thread tool. It's located under the hole drop down. Your pipe OD must be correct. Refer to the holes spreadsheet - for ANSI it's ANSI Inch.xlsx.
Once you are able to create the threads, create a drawing of your part. Use the callout tool or dimension tool. I use the callout tool and then in the properties dialogue, select the "thread size" button in the feature reference group or type in %TS and Solid Edge will pull up the thread size.
