simple hello.asm (NASM) not compile in x64, plz help

hello:
I copied a simple hello.asm  (NASM) assembly program from 
www.tldp.org/HOWTO/html_single/Assembly-HOWTO/
try to compile and run on my linux 64(ubuntu14.04), but I got errors:

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ld -s -o heworl heworl.o 
ld:i386 architecture of input file *.o is incompatible with i386:x86-64 output
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please help,(how to make it compile and run on my 64 platform rather than ask me switch to 32 bit platform),thanks a lot ina dvance, eric

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