Clarification about lightning network When I run a lightning node, I have to set up a lightning channel with, for example, a highly connected node. 

Here a first question: When I set up a lightning channel with a node, have I need to put some bitcoins in it?

Then, if I wanted to buy something using lightning network (for example, a sticker from Blockstream), will I have to open another lightning channel with Blockcstream? Or the previously synced channel will be used to let me buy from Blockstream? 

Thank you.
When I set up a lightning channel with a node, have I need to put some bitcoins in it?


Generally, yes. The person who initiates the channel creation process (i.e. the person that says "I want to open a channel with you") is the one who funds the channel.


  Then, if I wanted to buy something using lightning network (for example, a sticker from Blockstream), will I have to open another lightning channel with Blockcstream? Or the previously synced channel will be used to let me buy from Blockstream? 


Not necessarily. If your channels are connected to other nodes who have channels with other nodes and eventually a channel with the merchant (which is likely the case), then you do not need to open any new channels. You can make your payment route through the Lightning Network and it will reach the merchant.