Hi there !
I'm new in Arduino world, and I'm trying to do a little audioplayer : Simple SD Audio Player with an 8-pin IC
As I'm n00b, I want to make the simple mono model.
Following this tutorial : Programming ATtiny ICs with Arduino Uno and the Arduino IDE 1.6.4 or above – 42 Bots , I successfully flashed the "blink" sketch into the ATtiny45 \o/
Next step : doing to flash the audioplayer firmware into the ATtiny45, but as you can see (in the first
link I gave), it is a ".hex" file.
And I have no idea about how to do this, can someone help me please ?
Oh, always using Arduino as ISP, of course. 
In the IDE preferences if you set show verbose output during upload, and upload the blink sketch, it will show the avrdude command line used for uploading the blink hex file. Copy that command line to your OS command line prompt and make the appropriate changes to upload the hex file of your choice.
Good idea, thank you !
I'll give it a try soon.
I have another question, there is a part I don't understand.
If you have read the project's page, I get lost at the fuses point.
Here : 
1- Is there only one line to remove, or two ? I get confused because of the red "}"
2- Do I really need to program (or not) the fuses ?
Well I don't know about that. Project and tutorial page quality varies a lot. It seems to me if they wanted you to have the hex file with a line or two taken out, they would just give you the corrected and proven-to-work hex file. You'll probably need to experiment if you are determined to use that tutorial. You probably need to set the fuses because most programs are written to expect the fuses set with specific values.
Ok
The fact is : right now, I don't have any idea about what is the purpose of burning or not
burning the fuses.
But you're truly right, I just need to experiment more further. Thank you for ur advice, pal 