The particle へ is used to mark a destination, indicating the direction of movement towards a specific location or person. While へ and に can often be used in the same way, へ carries a subtle nuance. It highlights the path or journey toward the destination, whereas に focuses more directly on the final point of arrival. へ is always placed directly after the noun that functions as the destination.

• 彼(かれ)は国(くに)へ帰(かえ)る。
  He will return to his country.
• 来週(らいしゅう)京都(きょうと)に行(い)く。
  I will go to Kyoto next week.

In the sentences above, the distinction might seem minor. However, へ implies a sense of traveling through the space between the start and end points, while に simply marks the final location. This nuance is what makes phrases like '[place] へ ようこそ' feel welcoming and polite, as it acknowledges the guest's effort in traveling to that place.

• 北海道(ほっかいどう)へようこそ！
  Welcome to Hokkaido!
• 私(わたし)のブログへようこそ。
  Welcome to my blog.

When used with something like a blog or a store, this expression conveys appreciation for the 'journey' the person took to arrive there—in other words, 'thank you for choosing to visit us out of all the other options available'.