I would like to know the same thing!!! The new website is slick, but I forgot to charge my Garmin last night and I used Map My Run to figure out how far I went. But when I came to Connect.Garmin.Com I can't find the "Manual" entry link that used to be on the old site. I really hope I'm just not seeing it, because if it's been removed permanently that is a deal breaker :(
In the modern Garmin Connect, click the three horizontal line icon on the left. Move your mouse up to Activites and then over to the > symbol. You will see a sample of what the activities widget will look like. See the + symbol? Good; now you know what you're looking for. If you don't have an activities widget on your dashboard, you can add one now by clicking the Add to Dashboard button.
The Manual Activity function seems to be back on the Activies page.
TRAVIS.VITEK's post on entering a Manual Activity works pretty much as written. I am just slow, it took awhile to figure it out.
This is cool I entered a manual activity via Travis' instructions, went to lunch, came back, relogged on and now there is a Manual Activity option right next to Import on the Activities page just about where it was in the old interface.
Before and After:
I do not know if the two screen snips above will work.