Some thing like your problem:

Shift + S and select, Selection to cursor (Be sure to use it in Object mode)

It will moved to center as on your 3d cursor. (if your 3d cursor is not in center already try Shift + S and select, Cursor to center)

Now you may adjust the location of your model along z axis manually, I hope it will not difficult for you.

Best of luck!

Some thing like your problem:

Shift + S and select, Selection to cursor (Be sure to use it in Object mode)

It will moved to center as on your 3d cursor. (if your 3d cursor is not in center already try Shift + S and select, Cursor to center)

Now you may adjust the location of your model along z axis manually, I hope it will not difficult for you.

Best of luck!

Updated: You may try to hit Ctrl + A and apply location and also please follow the steps as shown below:

Some thing like your problem:

Shift + S and select, selection to cursor (Be sure to use it in Object mode)

It will moved to center on your 3d cursor. (if your 3d cursor is not in center already try Shift + S and select, cursor to center)

Now you may adjust the location of your model along z axis manually.

Best of luck!

Some thing like your problem:

Shift + S and select, Selection to cursor (Be sure to use it in Object mode)

It will moved to center as on your 3d cursor. (if your 3d cursor is not in center already try Shift + S and select, Cursor to center)

Now you may adjust the location of your model along z axis manually, I hope it will not difficult for you.

Best of luck!