Date Calculation from current time

I am very new to appian , 
I am trying to calculate the value of " To Date field "  and show the date in the calendar , I want to add the number of days that i saved in the local varibale (local!days) to the current date to find the new date ,

how can i do that? 

Here is what i wrote for the " days" field 

a!integerField(
label: "Deposit Days",
labelPosition: "ABOVE",
value: a!match(
value:local!periodtype,

equals: 1,
then:{local!days},
equals: 2,
then:{if(not(isnull(local!weeks)),(local!weeks*7))},
equals: 3,
then:{ri!numberofmonths*30},
equals: 4,
then:{ri!numberofyears*365},
equals:null,
then:{false()},
default: then:{false()}

),

saveInto:{local!days,a!save(local!despositdays,local!days)},


required: false,
disabled: a!match(
value:local!periodtype,
equals:1,
then:{false()},
equals:2,
then:{true()},
equals:3,
then:{true()},
equals:4,
then:{true()},
equals:null,
then:{false()},
default: then:{false()}

/*DAYSSSSSS CODE */

TO DATE FIELD:
a!dateTimeField(
label: "To Date",
labelPosition: "ABOVE",
value: 
saveInto:

required: false
)