Translation:I ran all morning! Now I am having a rest.
'I've been running all morning' is another perfectly acceptable form of the past tense in English (past continuous) but I was marked wrong. Reported. In case a moderator is reading this: רצתי could be translated in a number of ways in English: I ran, I have run (or I've run), I have been running (or I've been running), I was running, I had run (or I'd run), I had been running (I'd been running). Some of these are used less often in US English than say, in Britain or Australia, so some Israelis may be less familiar with these forms, but they are grammatically correct and used a lot in many English-speaking countries. This applies to any verb in the past tense in Hebrew, and which form is used will depend on context. Because there is no specific context here, any of these possibilities should be accepted as correct.
It's not correct idiomatically. In English, we don't include 'all' in that particular phrase. We say 'all morning' - that's just the way we say it. It's the same 'all night' - it's not 'all the night'. 'I worked all morning.' 'I slept all night.' 'I played football all afternoon.' 'I learned Hebrew all evening.' And so on. You could say 'I slept all through the night', or 'I learned Hebrew the whole evening', but not 'all the night' or 'all the evening'.