Please can you tell me how to put my own exercises in weight training workout?
You can't. It has been suggested for years to allow user's to input any exercises that aren't included in Garmin's limited list, but for some reason the request has been ignored. Case in point, there are 44 different strength exercises you can do with the TRX. Garmin only list 4 TRX exercises and 4 suspension exercises on their list. Combination weightlifting exercises has the same problem. I really don't understand why the user is unable to edit the exercise type.
This is a peer-to-peer forum and not an official support site. Some Garmin employees may visit the site, but it's not the formal channel to address an issue. You can request the feature using the link below, but I don't think it'll do any good. I've done it at least 10 times over the years and I know many others have also.