E13 is the current value of your fixed assets.
E34 is the cumulative profit or loss for all previous years.
It's possible these two are similar but they aren't related. The "Retained Profit and Loss" from the previous years Balance Sheet should be copied into the following years opening figure, E34 in DIY Accounting.
Capital Reserves: You can move funds from the P&L into a capital reserve to use for significant asset purchases you might want to budget for separately. The idea is that it has been set a aside and wont get dripped into automatically if you make a loss.