How to assign value to StringEdit from class in AX 2012 ?

Hi Master,

How to assign value to StringEdit from Class. What I have to declare an object form in class ?

I tried Code like this,( in class) :

LedgerJournalTransVendInvoice ledgerJournalTransVendInvoice =  new ledgerJournalTransVendInvoice();

ledgerJournalTransVendInvoice.DocumentNum.Text('Value');

where I can put this code correctly ? I have tried this code but still error,? Can someone share. What should I do ?

Thanks,

Agung