To raise the exchange rate of its currency, would a central bank buy or sell foreign assets?

Question:

To raise the exchange rate of its currency, would a central bank buy or sell foreign assets? What would be the effect on the monetary base? What would be the effect on domestic interest rates?

Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...