Welcome Scaredswimmer--
Just a quick look online at your vaping device tells me it's not going to be that well suited for DMT use. You'd be better off using a regular pipe or ideally a Glass Vapor Genie. Some also use bongs with great success.
You'll have a hard time getting a consistent hit with a regular vape pen-- they're just not made to use for this purpose and you'll probably also waste good spice.
As for advise, spend the 20 bucks on a Gemini (or similar) mg scale (as in, increments of .001g ) because it's especially important to weigh accurately (especially when you're new).
START SLOW.
You're not in a race to experience anything-- take it easy and feel your way into it at an easy pace.
It's instinctive for most people to be very tense when using DMT early on. It's normal. Even after almost 15 years and thousands of uses, my heart usually still pounds just as I get ready to take it-- your body somehow knows what you're about to do--it's normal and you just have to have the confidence that you have used the right amount, have chosen good safe music (if it applies to you-- I almost always bed with music) and are in the right positive mindset. DMT is physically safe-- but using too much can be nothing less than catastrophic to your mind. This is meant to caution you, not scare you. Work your way up.
Then, just let the experience guide you. If you use too much, you will be unprepared for what happens. That's normal. I'll not waste time here with description other than to say that there is a threshhold that you will pass where it becomes something fundamentally different than low doses-- but you will understand when it happens.
Stay positive, be deliberate, use the right tool for the job, and read as much on this forum as you can-- there is great wisdom here, and many good friends with good advice and shared experiences.
Good luck to you!!