After studying the beginner courses and made a few practice databases, i would begin be going over the beginner videos again, but building the one you want. That's what i did.

From what you described, you'd hugely benefit from the expert series as well. Beginner is good as an introduction and gets you started but you won't really have all the skills you need until completing the expert series. I'm currently up to Expert 7 and am supporting an automated database which handles all the work for a small life insurance company.

Advanced and developer are only really if you want to take database design to a career level so no need to worry about them for now. I can highly recommend the Learning connection method as you'll get all the lessons at half price delivered once per week (You can change this to suit you, just ask Rick). Also, if you find after a few expert classes you are happy with what you know, you can cancel anytime.

Back to your question, it isn't so much about "type" as it is just building and going along. You'll start out with a basic form for entering and displaying data and your tables and queries to manage that data. From there it'll take on a life of its own and build as requirements set in. That's the beauty of database design.

Hi Dan and thank you for the help. I am thinking about taking the expert class also but for that I need to have money, in order to have money I need my business to work smoothly, in order to make my bussiness run smoothly I need my database finished and working ;-)
I made a Main form ( with Ricks courses offcourse) when I click on the customers button it opens a form with two subforms called "past conversations" and "reservations" and that works fine for me.
I just struggle with one more thing ... When a course is finished I have a complete list of tasks I still have to do (administrations  etc) I wonder if it is possible to make a kind of tasks form that only opens when I mark my reservation as finished?

Completely understand where you're coming from. Strongly recommend going through the tech help and fast tips - they're free and packed with info (The only downside being, is at the beginning of the videos, there will be pre-requisit videos to watch since they aren't in any logical order).

As for your list of tasks, to automate the opening of another form requires some simple understanding of VBA. At your current position, my recommendation would be to create a table (e.g. Called TasksT) with three fields:

TaskID - Autonumber
TaskName - Short Text
TaskDone - Yes/No

Then, do a continuous form and set the source to that table. No need to include the ID. See pictures.

Finally, you can optionally add a button to any other forms to open that one by using the command button control. No coding/macros required. Everything i did is covered in beginners.

If you get stuck, let us know

Thanks for the help Dan, I do have a simple basic understanding of VBA so that is no problem. The automation i mensioned is because I don't want to be that task form ALWAYS open. there are times several reservations will be completed at the same time and I don't want 5 or 6 task forms open at the same time you see.
I tried to add a comand button in a subform but it doesn't work when I put it in the subform only when I put it in the mainform

My experience is quite limited with sub forms so will have to see if one of the other guys can help with that. i'm sure it's an easy solution. Best of luck

So you just want to hide the subform unless it's marked as completed? If I'm understanding correctly?

Just set the subform to visible:no and do this in the on current event and the after-update event of the checkbox that marks it "complete"

subformname.visible = true