Transactions on the Forex market are made on Spot terms. It means that all the deals are made with the actual delivery of the currency the next workday after their execution. However, there is no need for the real delivery of the currency in case of speculative trading (speculative trading is actually something that you are about to start). If you execute order during one workday, the delivery is canceled. It does not cause any problems. But what if you have to leave your order open for more than one day?
For Wednesday-Thursday rollover, swap is deducted/added in a triple size (for Wednesday, Saturday, Sunday).
The operation of the rollover of the position which is called Swap has been created for this purpose. The basis of this operation is that you need to "close" the order and reopen it at the close price. At the same time, funds that are equal to the swap size are deducted from or added to your account. The swap size depends on the interest rates of the Central Banks and the range of other factors. Because the interest rate is set by the Central Bank of each country, this leads to a situation wherein the difference between the interest rates of various currencies may be quite considerable. The calculation of the swap rate is carried out in the view of this difference.
Swap is calculated automatically in the end of every trading day. For Wednesday to Thursday rollover, swap is deducted/added in a triple size (for Wednesday, Saturday and Sunday). In the MetaTrader 4 trading platform you can see all the current swap rates of every currency pair (to do this, right click and choose "Symbols" in the "Market Watch". Choose the currency pair you need in the appeared window and click the "Properties" button. Swap rates of long and short positions are displayed in pips).