Hi Brett,
Thank you fr your purchase.

If you wish to apply this code to all of your wpDataTables tables, you can put it in “Custom wpDataTables CSS” text area on wpDataTables Settings page,
or if you wish to apply it only on specific pages, you can put it in between style tags 

 .wpDataTablesWrapper table.wpDataTable td, .wpDataTablesWrapper table.wpDataTable th
{ text-align: center !important;}

Hi Brett,

Yes there is some class with high priority. So please replace that css rule for th

.wpDataTablesWrapper table.wpDataTable th

with this

.wpDataTablesWrapper table.wpDataTable th.wdtheader

About the styling the specific cell you can use Conditional formatting. You can read more about this on this link.

Hi Brett,

Sorry for late response. 

We are located in Serbia and our working time is from 10:00 to 17:00 CET. business days.

Yes because class wpDataTablesWrapper have to start with small letter.
Just change that first letter from W to w.

.wpDataTablesWrapper table.wpDataTable td,
.wpDataTablesWrapper table.wpDataTable th.wdtheader

{ text-align: center !important;}

In that column where you have this caps letters in conditional formatting you have to make condition for every text in caps. Example:(attachment 1) and then make that class test in Custom wpDataTables CSS under the "Custom JS AND CSS" (attachment 2) We make example for two cells, but if you have more then you have to add them also in conditional formatting.