go to 3d

I am using 2d model space i want go to 3d what i will do ?

If you are asking how to switch to a 3D view, then call the VIEW command, select Preset Views and chose one of the Isometric views.

If the question is how to model items in 3D, then I suggest to find some tutorials on this mater and follow them.

First switch to the 3D Modeling workspace.

 

Do you know how to manipulate the orientation of your UCS?

So many different ways to get there. Yet another would be to use the VIEWPORT CONTROLS in the upper left hand corner of your viewport, these controls provide a wealth of different options, without using the ribbon, any toolbars or the commandline.

Go to one of the Isometric views as Mircea suggested, and watch your horizons and potential grow before your virtual eyes. Open up your MODELING toolbar or PANEL (on the ribbon) and have a bit of a play with the commands there. No doubt you will want to access some of the wealth of available free tutorials on this site and elsewhere.

Your Autocad help will also provide a great deal of useful information. Once it all starts to make a bit of sense then open your SOLID EDITING toolbar and consider those operations. Spend a couple hours learning how the different tools work.

If your tooltips are not turned on , they probably should be, as shown in the image. Good luck, the sky is the limit, and in modelspace there is none, so relax and have a little fun.

Right-click below the menu bar and select the view.

FYI: O.P. has AutoCAD MEP on their profile. Might be an MEP related question.

Certainly sounds like it, go get him Tannar.

Is it appreciably different?

Is it appreciably different?

Yes it's very different only if the O.P. is asking about 3D with the AEC Objects and additional 3D tools that come with AutoCAD MEP. A vertical product of AutoCAD has far more functionality and tools available than OOTB 3D tools and modeling procedures. That's why I was asking for more clarity.